Nowadays, in ophthalmic surgery, replacing an opaque natural eye lens with an artificial lens is one of a number of routine procedures. However, this procedure requires that the surgeon has a very steady hand and has had a great deal of practice.
For this reason, hand-operated devices referred to as injectors are known which permit a certain degree of guiding when fitting the artificial lens. These known injectors generally have a grip body, and a plunger which can be displaced in the grip body via a thread. In the front area of the grip body there is a lens holder into which an artificial lens to be inserted is placed. By rotating the plunger, this lens can then be pushed through a front opening of the lens holder, the lens being folded in the process, if appropriate. By further advancing the lens, it is introduced in the folded state into the eye. An injector of this kind is disclosed, for example, in U.S. Pat. No. 5,643,276.
Moreover, the applicant's European patent application EP 01 810 823, which is still to be published, describes a hand-operated injector which permits use by one hand but nevertheless guarantees exact guiding of the plunger. In this injector, the plunger is mounted so as to be laterally displaceable in a ball-bearing bush. The precise lateral displacement is ensured by a guide groove into which a guide element arranged in the grip body engages. In one embodiment, the plunger is laterally displaceable but fixed in terms of rotation In another embodiment, the plunger has a spiral in order to permit a rotation of the plunger at the end of the insertion movement. This makes it easier to insert the artificial lens, in particular to unfold it in the eye. However, this rotation is predetermined by the design of the injector, in particular of the spiral.